Safety edge for a door



6, 1969 N. K. MILLER 3,462,885

SAFETY EDGE FOR A DOOR Filed Oct. 17. 1967 FIGB 34 INVENTOR NORMAN K. MILLER M/ 1 34 FIG. 5

ATTORNEY United States Patent i 3,462,885 SAFETY EDGE FOR A DOOR Norman K. Miller, Havertown, Pa, assignor to Miller Brothers, Concordville, Pa, a partnership composed of Karl K. Miller, Arsen K. Miller, and Norman K. Miller Filed Oct. 17, 1967, Ser. No. 675,805 Int. Cl. E06!) 7/16; A47f 3/04 US. Cl. 49488 Claims ABSTRACT OF THE DISCLOSURE A safety edge for a door wherein a resiliently compressible structure is enclosed by a flexible, impervious sheet covering, and an electric heater is associated with the compressible structure interiorly of the cover.

BACKGROUND OF THE INVENTION As is well known to those versed in the art, safety edges for doors, say overhead doors as in aircraft hangars, and other doors requiring safety edges, there is often the problem of extreme temperature conditions. For example, in doors subjected to conditions of freezing temperatures, there are presented the problems of icing which may prevent desired door movement, as in sticking of the door edge to the door jamb. Also, the cushioning usually provided along one edge of a door by such safety devices tends to rigidify or stiffen and lose its essential cushioning effect.

SUMMARY Accordingly, it is an important object of the present invention to provide a safety-edge construction for a door which overcomes the above-mentioned difficulties, automatically insuring the absence of icing conditions along the door edge so that freedom of movement is not impaired, and wherein the desirable resilient compressibility or softness of the door edge is maintained, even under ambient conditions which would otherwise rigidify the structure.

It is another object of the present invention to provide a safety edge having the advantageous characteristics mentioned in the preceding paragraph, which is extremely simple in construction, durable and reliable throughout a long useful life, and which can be economically manufactured and installed, with little or no maintenance required.

Other objects of the present invention will become ap parent upon reading the following specification and referring to the accompanying drawings, which form a material part of this disclosure.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, which will be exemplified in the construction hereinafter described, and of which the scope will be indicated by the appended claims.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a front elevational view showing an overhead door having a safety edge of the present invention incorporated therewith.

FIGURE 2 is a partial transverse sectional elevational view, enlarged for clarity, taken generally along the line 2-2 of FIGURE 1.

FIGURE 3 is a longitudinal sectional elevational view taken generally along the line 33 of FIGURE 2, and broken away to conserve drawing space.

FIGURE 4 is a perspective view in transverse section, partially broken away for clarity of understanding.

FIGURE 5 is a perspective transverse sectional view 3,462,885 Patented Aug. 26, 1969 ICC DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more particularly to the drawings, and specifically to FIGURE 1 thereof, a building is generally designated 10, having therein an opening or doorway 11. A door 12 is located in the doorway 11, and may be of the overhead type having its lower side or edge provided with a safety edge of the present invention, generally designated 13. The overhead door 12 may be provided with a swinging door 14, say at one lower corner of the overhead door, as seen in FIGURE 1.

As best seen in FIGURES 2 and 3, the safety edge 13 extends along the lower edge 16 of the door 12, being longitudinally coextensive therewith. Thus, the safety edge 13 is movable with the lower door edge 16 into and out of engagement with a ground surface or door jamb thereon.

The safety edge 13 includes, interiorly thereof, an elongate resiliently compressible structure 17 extending generally along the door edge 16 and projecting outward therefrom. The resiliently compressible structure 17 may be of generally rectilinear overall configuration, including a generally rectangular inner or upper member or pad 18 adjacent and substantially congruent to the face of lower door edge 16. The pad 18 may be fabricated of foam rubber or other suitably resiliently compressible material. An intermediate pad 19 of a rectangular-outline configuration substantially congruent to that of upper pad 18 may be arranged immediately below the upper pad. The intermediate pad 19 may have a series or row of thru apertures or openings 20, and the intermediate pad 19 may also be fabricated of rubber foam or other suitably resiliently compressible material. On the underside of the intermediate pad or member 19 is a lower member or pad 21, also of a rectangular-outline configuration congruent to that of the intermediate and upper pads 19 and 18. The several members or pads 18, 1'9 and 21 are suitably secured together, as by rubber cement or the like, and a pair of flexible compact sheets or strips 22 and 23 are arranged in spaced faced relation on the upper and lower sides, respectively of the intermediate pad 19. That is, the upper conductor strip 22 is interposed between the upper pad 18 and intermediate pad 19, extending across the intermediate-pad openings, While the lower conductor strip 23 is located between the intermediate pad 19 and lower pad 21, also extending across the intermediate-pad openinsg and in spaced confronting relation through the intermediate-pad openings with the upper conductor strip 22. As the several members or pads 18, 19 and 21 are of a normally resiliently compressible material, it will be appreciated that upon depression or compression of the structure 17, as by engagement with an obstruction in the doorway 11, the flexible contact strips 22 and 23 will be caused to move through one or more of the openings 20 into electrical contact with each other. By means of conductors or leads 24 and 25, respecttively connected to conductor strips 22 and 23, and electrically connected by suitable means (not shown) to a motor circuit, operation of the door is stopped or reversed to prevent injury or damage to the obstruction. The conductor strips 22 and 23 may extend the entire length of the compressible structure 17, or less than the entire length, as shown in FIGURE 3, terminating short of the walk-through door 14, so as not to be unintentionally actuated by users of the walkthrough door.

Effectively completely encasing the foam-rubber struc ture 17 is an outer covering 27 of flexible sheet material.

The outer covering is fabricated of a suitably abrasionresistant and otherwise durable sheet material, such as a woven fabric impregnated with plastic, or the like, and may include a main sheet 28 extending about the bottom and up opposite sides of the compressible structure, terminating in upstanding opposed margins 29 for connection to the door 12. A top piece 30 extends over the structure 17 between and secured to the upper side margins 29, while end pieces 31 extend across and close opposite ends of the cover 27.

Also substantially completely encasing the compressible structure 17, and located interiorly of the cover 27, is an inner lining 33. The inner lining 33 is advantageously fabricated of a highly flexible and punctureor tear-resistant sheet material, such as terephthalate, or other suitable material. The inner lining is similarly fabricated of a main piece 34 extending across the lower side of the structure 17 and up along opposite sides thereof, terminating in upper edge margin 35 extending above the compressible structure. A top piece 36 extends over the compressible structure 17 between and is secured to the opposite margins 35 to the main piece 34, while end pieces 37 are secured across opposite ends of the structure 17.

In addition, an elongate heater is generally designated 40, and extends along the lower or underside of the compressible structure 17, remote from the door 12. The heater 40 is advantageously electrically energized, and preferably includes a thermal resistor or heating element 41 having a resistance dependent upon ambient temperature. Specifically, the resistance of heating element 41 is variable so as to decrease with decreasing temperatures and increase with increasing temperatures. Such a thermal-resistance heating element may be fabricated of a flexible woven strip of fabric, say woven of glass fibers, and a conductive material impregnated therein. For example, a conductive silicone polymeric elastomer may be vulcanized into the woven strip or tape, the conductors may be incorporated in the edges or selvage of the tape. However, other suitable flexible thermal-resistance heating elements may be employed. Suitable conductors or leads 42 and 43 are shown connected to the heating element 41 and extending therefrom externally of the outer cover 27 for connection to a source of electricity.

In addition to the heating element 41, the heater 40 may include an enclosure or sheath 44, say of suitably flexible insulating material, such as vinyl, terephthalate, or other. The heater or heater assembly 40, thus consisting of the heater element 41 and sheath 44, extends along the underside of the compressible structure 17, advantageously being located between the outer cover 27 and inner liner 33, as best seen in FIGURE 4, and may be longitudinally coextensive with the compressible structure. In this manner, heat from the heater 40 is transmitted both downwardly through the outer cover 27 to prevent freezing of the latter to a door jamb, or the like, and is also transmitted upwardly or inwardly to the compressible structure 17 in order to maintain the desired resilient compressibility or cushioning of the structure.

In the embodiment of FIGURE 5, the resiliently compressible structure 17, the outer covering 27, and the inner lining 33 may all be substantially identical to correspondingly numbered component parts of the first-described embodiment.

However, the heater or heater assembly 40a of the embodiment of FIGURE includes a heater element 41a, which may be substantially identical to the heater element 40, but is located in direct facing engagement with the'outer surface of the main part 34 of inner liner 33, on the underside of the structure 17. An additional strip of flexible insulating material 44a is interposed between the element 41a and the main sheet 28 of the cover 27, extending laterally beyond the heating element 4 and having its longitudinal edges secured to the inner lining 33. Thus, the insulating strip 44a combines with the inner lining 33 to define a casing or sheath for the heating element 41a. The embodiment of FIGURE 5 provides effective electrical and physical protection to the heating element 41a at a savings in material.

From the foregoing, it is seen that the present invention provides a safety edge for a door, which safety edge fully accomplishes its intended objects and is well adapted to meet practical conditions of manufacture, installa tion, maintenance and use.

Although the present invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be made within the spirit of the invention and scope of the appended claims.

What is claimed is:

1. A safety edge for a door, comprising an elongate structure for extension along a door edge projecting outwardly from the door edge surface, said structure being resiliently compressible in all directions, a cover on said structure of flexible impervious sheet material, and an elongate flexible electric heater strip extending along said structure interiorly of said cover remote from said door edge, said heater comprising a generally fiat flexible fabric strip impregnated with conductive material and having a width approaching that of said structure, and an impervious sheath engaged about said strip, whereby heat is transmitted from said heater to said cover and structure to maintain the cover free of adjacent surfaces and preserve the resilient compressibility of said structure under freezing conditions.

2. A safety edge for a door according to claim 1, said heater comprising a thermal resistor having decreasing resistance with decreasing temperature, for increased heat transmission to said cover and structure at lower temperatures.

3. A safety edge for a door according to claim 1, in combination with a pair of flexible normally spaced contacts interiorly of said structure and movable into engagement with each other upon compression of said structure.

4. A safety edge for a door according to claim 1, in combination with a lining of impervious flexible sheet material extending about said compressible structure inwardly of said cover, said heater being located between said lining and cover.

5. A safety edge for a door according to claim 4, in combination with a protective sheet extending longitudinally along and between said heater and cover and secured to said lining on opposite sides of said heater, said protective sheet combining with said lining to define a sheath enclosing said heater.

References Cited UNITED STATES PATENTS 2,507,895 5/1950 Foxtow 49-475 X 2,809,402 10/ 7 Southworth.

2,858,408 10/ 1958 Barroero 219-218 X 3,055,193 9/1962 Smith 49-478 X 3,133,167 5/1964 Miller ZOO-61.43 3,135,100 6/1964 Taylor et a1. 219-218 X 3,210,496 10/1965 Gary ZOO-61.43 3,315,050 4/1967 Miller ZOO-61.43

DAVID J. WILLIAMOWSKY, Primary Examiner PHILIP C. KANNAN, Assistant Examiner U.S. Cl. X.R.

4,92.7; 62-248, 275; ZOO-61.43; 219-213, 218 

